This application claims the priority of German Patent Application No. 197 22 097.5, filed May 27, 1997, the disclosure of which is expressly incorporated by reference herein.
This invention relates to a heat exchanger for a motor vehicle, having a fin/tube block with flat tubes which are provided on opposite sides with tube ends which are widened such that transversely extending, mutually adjacent wall sections of the tube ends flatly adjoin one another and the tube ends of a row are aligned with one another, one flow box or tank respectively being placed on the tube ends on both sides and ending flush with corresponding longitudinally extending wall sections of the tube ends, and to a heat exchanger arrangement for a motor vehicle having at least two heat exchangers arranged next to one another in a flow-through direction.
German Patent Application DE 195 43 986.4, which is not a prior publication, describes a heat exchanger which has a fin/tube block with flat tubes with tube ends which are widened to respective rectangular cross-sections. The tube ends are widened such that they adjoin one another flatly with their wall sections extending transversely to the longitudinal direction of fitted-on flow boxes or tanks, and such that the respective lateral longitudinally extending wall sections of the tube ends are aligned with one another and end flush with the corresponding wall areas of the fitted-on flow tanks. By brazing together the adjoining wall sections and wall areas, the sealing of the flow tanks is achieved. The flow tanks are used as collector or distributor tanks. In addition, this German application, which is not a prior publication, discloses a heat exchanger arrangement having two heat exchangers, one constructed as a vehicle radiator and the other constructed as a condenser. These two heat exchangers are arranged directly next to one another in the flow-through direction of the air and are connected with one another in the area of the respective flow tanks by corresponding connecting devices.
It is a primary object of the invention to provide a heat exchanger as well as a heat exchanger arrangement of the initially mentioned type which permits operationally reliable manufacturing and a simple and space-saving construction.
With respect to the heat exchanger, this object is achieved in that the mutually adjacent, transversely extending wall sections of the tube ends adjoin one another in a form-locking manner. It is therefore possible to achieve a precise mutual alignment and fixing of the tube ends during pre-assembly of the heat exchanger, that is, before the brazing-together of the individual components. Tolerances as the result of a lateral offset of individual tube ends can be avoided. In addition, the form-locking contact of the wall sections with one another results in an enlarged contact surface which in turn results in increased safety of the brazed connection.
According to one feature of preferred embodiments of the invention, the longitudinally extending wall sections of the tube ends which face flow boxes or flow tanks form-lockingly adjoin corresponding wall sections of the flow boxes or flow tanks. This further improves the pre-assembly of the heat exchanger because the flow boxes, relative to their longitudinal direction, can also be fitted onto the tube ends in a precisely positioned manner and can be fixed in the longitudinal direction by the form closure. In addition, the form-locking contact ensures an enlarged contact surface which further improves the tightness and the safety of the subsequent brazed connection between the flow boxes and the tube ends.
According to a further feature of preferred embodiments of the invention, the corners of the widened tube ends are provided with radii between 0 and 2 mm. In this case, the widened tube ends preferably have a rectangular shape and can additionally be provided with correspondingly shaped wall sections. The preferred radii ensure that only extremely narrow gaps remain between the adjacent tube ends also in the area of the exterior sides. These gaps can be completely filled by brazing during the brazing operation so that the tight brazed connection is ensured mutually and particularly with respect to the lateral wall areas of the flow boxes.
According to a further feature of preferred embodiments of the invention, the tube ends are each widened asymmetrically with respect to the longitudinal center planes of the assigned flat tubes. As a result, it is possible to implement special arrangements of components of the heat exchanger without affecting reliable functioning of the heat exchanger.
According to a further feature of preferred embodiments of the invention, the circumference of the widening of each tube end corresponds to the circumference of the assigned flat tube, plus or minus 30%. The negative relationship between the circumference of each flat tube and the circumference of the assigned widened tube end is the particular result of a folding of the wall of the tube ends which is double-walled in sections.
According to a further feature of preferred embodiments of the invention, the transverse-side wall sections which face the adjoining tube ends have a height H.sub.1 between 0.3 and 2 times a separation distance T of the flat tubes, specifically 0.3T.ltoreq.H.sub.1 .ltoreq.2T. This preferred dimensioning range permits a secure, tight connection between the tube ends as well as a sufficient stability of the whole fin/tube block.
According to a further feature of preferred embodiments of the invention, the flat tubes are aligned relative to the axis of symmetry of the widened tube ends in a diagonally extending manner. This further feature also permits a special arrangement of the heat exchanger in a motor vehicle, in which a diagonal arrangement of the heat exchanger within an engine compartment of the motor vehicle--relative to the normal driving direction of the motor vehicle--is advantageous.
With respect to the heat exchanger arrangement, the primary object of the invention is achieved by respectively assigning one common lateral part to the at least two heat exchangers on opposite sides. By using the common lateral parts, a simple and secure connection of the heat exchangers relative to one another is achieved, on the one hand, and a precise positioning relative to one another is achieved, on the other hand. Furthermore, simplified assembly and manufacturing are achieved for the heat exchanger arrangement with a reduced number of components.
According to a further feature of preferred embodiments of the invention, the flow boxes of at least one heat exchanger are designed to be open in their lateral areas, and the opposite lateral parts are each provided with at least one corresponding end section which projects into the respective lateral parts of the flow boxes and tightly closes the flow boxes off. As a result, it is possible to provide the flow boxes with a simple design because the tanks can be deep-drawn as simple U-profiles.
According to another feature of preferred embodiments of the invention, at least two heat exchangers have common fins extending along the total depth of the fin/tube block. This results in a simplified construction of the heat exchanger arrangement because the number of components is reduced and the fins directly establish the connection of the heat exchangers among one another.
According to yet another feature of preferred embodiments of the invention, the flow boxes of the at least two heat exchangers are provided with connecting sleeves which are aligned parallel to one another and in the same direction in a curved manner. This results in an arrangement of the connecting sleeves which is advantageous for the flow and also has a space-saving effect.
According to a further feature of preferred embodiments of the invention, insulation gaps are arranged between the tubes and/or the flow boxes. These insulation gaps are used for thermal insulation of adjacent heat exchangers with respect to one another, and the insulation gaps in each case separate the tubes from one another preferably along their whole lengths to the respective flow boxes. This further feature also includes the use of insulation gaps which are provided only in sections between the adjacent tubes and/or flow boxes. The insulation gaps preferably have widths between 1 and 10 mm.
Additional advantages and characteristics of preferred embodiments of the invention are reflected in the claims as well as in the following description of preferred embodiments of the invention which are illustrated by the drawings.